Last year, Charlie opened an investment account with $7200. At the end of the year, the amount in the account had decreased by 7%. (2) Fill in the blank to write the year-end amount in terms of the original amount. Write
your answer as a decimal.
Year-end amount = 1 x Original amount
(0) Use your answer in part (a) to determine the year-end amount in Charlie's account.
Year-end amount: $

For which intervals is the function positive? select each correct answer. [-6, -4) (6, 8] (-4, 0) (0, 6)

Here is their argument. given the obtuse angle x, we make a quadrilateral abcd with ∠dab = x, and ∠abc = 90◦, and ad = bc. say the perpendicular bisector to dc meets the perpendicular bisector to ab at p. then pa = pb and pc = pd. so the triangles pad and pbc have equal sides and are congruent. thus ∠pad = ∠pbc. but pab is isosceles, hence ∠pab = ∠pba. subtracting, gives x = ∠pad−∠pab = ∠pbc −∠pba = 90◦. this is a preposterous conclusion – just where is the mistake in the "proof" and why does the argument break down there?

1. during first 10 seconds 2. between 10 seconds and 35 seconds 3. during 35 seconds to 40 seconds